[sampster5000]

You're looking at low to medium light with the t8's I would say. You dont need the excel unless you're seeing algae. That is when I start to dose excel on my low tech tanks. I could be wrong but I thought yellowing of plants was a lack of macro nutrients? Possibly Potassium? I would dose macros when you see yellowing. You already have your traces with Flourish. Make sure not to add more Iron than needed. It is apart of Flourish as plants dont need so much of it.